a hidden gem in docker 18.06 – define your base CIDR for networks

Where you ever annoyed by the CIDR ranges used when a docker network was created without any further ipam spec (eg. in docker-compose.yaml)?

There is something hidden in the PR https://github.com/moby/moby/pull/36396: You are able to set the subnet CIDR from where docker networks are supposed to be created, plus you are able to define the size of the subnet,

Since I am a big fan of the 100.64.0.0/10 carrier grade NAT segment (it’s huuuge and a cool alternative to 10.0.0.0/8) and it’s a private network.